Clinical Treatment Guidelines for Severe Mitral Regurgitation

Classification and Diagnosis

The European Society of Cardiology recommends that echocardiography is essential for determining MR etiology, severity, and valve anatomy/function 2
Severe MR is defined by vena contracta ≥7 mm, effective regurgitant orifice area (EROA) ≥0.4 cm² for primary MR, regurgitant fraction ≥50%, and regurgitant volume ≥60 mL/beat 3
For secondary MR, thresholds may differ with EROA ≥0.3 cm² if the regurgitant orifice is elliptical in nature 4
The European Heart Journal suggests that cardiovascular magnetic resonance (CMR) should be used when echocardiographic measurements are ambiguous 1, 4
Exercise echocardiography should be considered for patients with exercise-induced symptoms to assess dynamic worsening of MR 3

The American College of Cardiology recommends that surgery is indicated for symptomatic patients with severe primary MR regardless of left ventricular function 2, 3
Surgery is indicated for asymptomatic patients with severe primary MR when LVEF ≤60% and/or LV end-systolic diameter ≥40 mm 2, 3
Mitral valve repair is strongly preferred over replacement when technically feasible 2, 3
The European Heart Journal recommends that surgery should be performed in a heart valve center with high repair rates (≥80-90%) 1, 4

Guideline-directed medical therapy (GDMT) is mandatory as the first step for all patients with secondary MR 3
GDMT includes ACE inhibitors/ARBs, beta-blockers, and mineralocorticoid receptor antagonists 2, 3
The European Heart Journal suggests that TEER should be considered for patients with severe secondary MR, LVEF >30%, persistent symptoms despite optimal medical therapy, and no indication for coronary revascularization 2, 5

Asymptomatic patients with severe MR require clinical and echocardiographic follow-up every 6-12 months 2, 3
Serum biomarkers (e.g., BNP) may help guide optimal timing of intervention in asymptomatic patients with severe MR 3, 4

For acute severe MR, management includes vasodilator therapy, inotropic support if hemodynamically unstable, and mechanical support with intra-aortic balloon pump if needed 2, 5
Risk stratification should include assessment of STS-PROM score, frailty, organ system compromise, and procedure-specific impediments 3